Frederick fitzgerald



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i I d YLettere Patent No. 211,475-, datedNevcngerl 25, 186'?.

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Be it known that I, FnEDEnIeK FITZGERALD, of Cincinnati, Hamilton county, Ohio, have invented e new and useful Vault-Light; and I hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawings, making part of this specification.

My invention relates to a form for the bullseyes or lenses adapted for insertion in asidewalk or deck or floor, to shed light into a room or vault below without obstructing the traihc over head or being liable to fracture thereby, and without trgnsmitting the images ofpassing objects.

Figure l-is a. perspective View of a lens embodying my improvements.

Figure 2 is a vertical section through u pavement provided with my improved lights.

Thelens may,vin its horizontal section, be circular, as shown, or in the form of a hexugon or a diamond or other shape. The upper surface has protuberancema, formed by intersection grooves, as shown or otherwise, for the twofold object ofpreven'ting slipping of' pedestriansland of obscuring the outlines of passing objects, while nt the same time inereasingilisrefractien and transmission-of lightr- The grond feature of novelty'in my iensV consists of the three ridge-like protuberonces bc c', from the underside of the lens, of which the ridgeor prov tubcrance 6 occupies a central position and possesses'the greatest prominence, the ridges c and c being arranged one on cach side of and parallel to b. All ofthe ridges have the rounded form indicated, and are separated by rounded valleys or depressions d d. The beneficial e'ec'ts o'f the ridges bcc are manifold and obvious. They cause a powerful and multifarious refractiori'an'd reection'of the light, which, besides diffusing it equally over the vault or chamber to be lighted, also enhances the aggregate illumination. They completely obscure the imagev or outline of objects passing over them, They serve to very effectually strengthen the lens. floor provided with such lenses isfound to transmit more light than the unoccupied holes, because the light which would be absorbed by the sides of the hole is both rcfraeted and reeeted downward by the lens. v

Compared with lenses having a smooth upper surface and angundcr surface composed of equal angulnr ridges, my lens possesses several important advantages. The rounded contour and vunequal depth of the bottom ridges or protuberances cause a remarkable and highly lnminousfrefrabtion, which penetrates -every part of the vnult. The deeply projecting central rib in particular, reaching down farthest into the room or vault, not only strengthens the lens where most necessary, but illuminates portions of the vault very slightly a`ected by the less prominent projections, while the roundedcontour, besides im arting strength, adds to the diversity of refraction and reflection, and is also free from the tendency to prisnriatsoidecoinposition of thetransmitted light, which occurs with the angular forms of lenses.

I claim herein as new, and of my invention- A vault-light, having a. grooved or otherwise uneven upper surface and an under 'surface composed 0f. c series of rounded parallel ridges b c c of unequal depth, with intervening rounded valleys d d', as and for the purposes set forth.

In testimony ofwbich invention I hereunto set my hand. 4

y FREDERICK FITZGERALD. Witnesses:

GEO. H. KNIGHT, JAMES ".H. LAYMAN. 

